Older overweight children consume fewer calories than do their healthy-weight peers

September 10, 2012

A new study by UNC pediatrics researchers finds a surprising difference in the eating habits of overweight children between ages 9 and 17 years compared to those younger than 9.Younger children who are overweight or obese consume more calories per day than do their healthy- weight peers. Among older overweight children, however, the pattern is reversed. The older children actually consume fewer calories per day than do their healthy-weight peers.

How to explain the counterintuitive finding?

Dr. Asheley Cockrell Skinner

“Children who are overweight tend to remain overweight,” said Asheley Cockrell Skinner, PhD. Skinner, alumna and adjunct assistant professor of health policy and management at UNC Gillings School of Global Public Health, is lead author of the study.

“For many children, obesity may begin by eating more in early childhood. As they get older, they continue to be obese without eating any more than their healthy-weight peers,” said Skinner, who also is research assistant professor of pediatrics in UNC’s School of Medicine. “One reason this makes sense is because we know overweight children are less active than healthy-weight kids. Additionally, this is in line with other research that obesity is not a simple matter of overweight people eating more — the body is complex in how it reacts to amount of food eaten and amount of activity.”

The results, published online Sept. 10 in the journal Pediatrics, also suggest that different strategies may be needed to help children in both age groups reach a healthy weight.

“It makes sense for early childhood interventions to focus specifically on caloric intake, while for those in later childhood or adolescence the focus instead should be on increasing physical activity, since overweight children tend to be less active,” Skinner said. “Even though reducing calories would likely result in weight loss for children, it’s not a matter of wanting them to eat more like healthy-weight kids — they actually would have to eat much less than their peers, which can be a very difficult prospect for children and, especially, adolescents.”

In the study, Skinner and co-authors Eliana Perrin, MD, MPH, associate professor, and Michael Steiner, MD, assistant professor, both in UNC’s pediatrics department, examined dietary reports from 19,125 children, ages 1 to 17 years, collected between 2001 and 2008 as part of the National Health and Nutrition Examination Survey (NHANES). They categorized weight status based on weight-for-length percentile in children younger than two years old, or with body mass index (BMI) percentile for children between two and 17, and performed statistical analyses to examine the interactions of age and weight category on calorie intake.